1. Field of the Invention
The present invention relates to testing of semiconductor devices, and more particularly, to a jitter measuring system and a total jitter measuring method in a high speed data output device.
2. Prior Art of the Invention
In general, jitter generated during operation of an integrated circuit is a type of noise. It is well known that such jitter can cause an error, or data loss, during operation. For this reason, accurate measurement of jitter generated in an integrated circuit device is desired.
In a high speed data processing device having a data speed on the order of 1 GHz or greater, e.g., a parallel/serial converter etc., in the case where total jitter of output data is measured by automated test equipment (ATE), it is highly desired during testing that jitter be measured to high accuracy. The total jitter of a system can be categorized into “DJ” (Deterministic Jitter) and “RJ” (Random Jitter). DJ jitter can be subcategorized into PJ (Periodic Jitter) and DDJ (Data Dependent Jitter). DDJ is generally composed of components of DCD (Duty Cycle Distortion) and ISI(InterSymble Interference).
In mixed tester systems, jitter measurement is commonly performed only for the determination of random jitter (RJ) and the periodic jitter (PJ) of data that has a lower speed below 1 GBPS. For this reason, data dependent jitter (DDJ), which is an important influence upon the total jitter characteristics cannot be measured precisely.
In order to measure the total jitter more precisely, conventionally, as shown in FIG. 1, a measuring instrument 20 is coupled with an ATE(automated test equipment) test device 30 as a mixed tester system. The measuring instrument 20 is connected to a data output device, such as a DUT (Device Under Test) 10. The test device 30 applies a control signal to the measuring instrument 20 through a GPIB (General Purpose Interface Bus), and receives measured result data. When the control signal is transferred to the measuring instrument 20 from the test device 30 through the GPIB, the total jitter measured by the measuring instrument 20 is transmitted to the test device 30.
The conventional method of measuring the total jitter (TJ) of a DUT 10 through a use of the measuring instrument 20 is capable of accurate measurement of the jitter, to a certain degree, however, this configuration requires the additional cost for a specific installment of the measuring instrument 20, and a great deal of stand-by time for the test device 30 in order to measure the jitter through the measuring instrument 20.
Such conventional jitter measuring method requires a measuring instrument capable of measuring the total jitter of high speed data at a rate of over 2.0 Gbps. For this and other reasons, there is a problem with cost increase due to the additional installation of the measuring instrument, and of a increase in time consumed by the test in gaining the result through the test device.